192 Mr. H. F. Baxter on the Force evolved 



glasses being half-filled with a weak solution of common salt, 

 covering the electrodes to the extent of an inch, two and some- 

 times three fingers of each hand were held perpendicularly in 

 the vessels, the middle finger resting upon the bottom of the 

 glass vessel. When first introduced, a slight tremulous motion 

 of the needle was observed; upon taking the fingers out of one 

 vessel and reintroducing them, and repeating this act, a slight 

 effect appeared, at first definite, but this soon subsided. Similar 

 effects were observed when the fingers of the other hand were 

 used in a similar manner. The fingers last introduced were not 

 always posilive ov negative to the others. Keeping the fingers 

 in, then moving one of the fingers so as to make the fluid rise 

 and fall upon the surface of the electrode in one vessel, produced 

 but little motion of the needle. After the fingers had been in 

 for some time, and the needle had become quite stationary, upon 

 contracting the muscles of one arm an effect ocem'red upon the 

 needle indicating the contracted arm to he positive to the other 3°; 

 by contracting the muscles of each arm alternately, the effect 

 amoimted to 5°. The result was definite, and the motion of the 

 needle steady. 



Du Bois-Reymond* considers that there are five circumstances 

 as influential in producing a current; viz. 1, temperature in- 

 egale ; 2, duree inegale de I'humectation avec le liquide con- 

 ducteur; 3, tension inegale de la peau; 4, lesion de I'une des 

 places de la peau ; 5, transpiration inegale. We could not refer 

 the effects we obtained to either of these circumstances ; — to the 

 tension of the skin, for instance. 



Three solutions were now prepared ; the first consisting of a 

 concentrated solution of common salt ; the second of sulphuric 

 acid, one part of strong acid to six parts of water ; and the third 

 of one part of liq. potassse (Pharm. Lond.) to four parts of 

 water. 



It was found necessary that the following precautions should 

 be strictly attended to. The solutions should be prepared and 

 well mixed previous to their use, and the electrodes covered to 

 the same extent. The hands and fingers should be thoroughly 

 clean ; to attain this object they were first washed with the ordi- 

 nary curd or Windsor soap, and afterwards well rinsed in common 

 water and wiped comparatively dry with a clean towel. The 

 same towels should not be employed when using the different 

 solutions, and it was found better to work on different days with 

 each solution ; for the liquids soaking in between the nails and 

 the fingers became a source of some difficulty to remove, and a 

 cause of some embarrassment in judging of the final result. 



* Bibliothique Universelle de Geneve, Juin 1853. 



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